There are three commonly used methods to determine trigger pull:
- Trigger weights
- Spring scale
- Digital scale
Laboratory protocols may determine the method that should be used to measure trigger pull.
|When testing the trigger pull of a revolver, each chamber of the cylinder should be measured, noting any variations.
Trigger weights are the most commonly used method of determining trigger pull. The system consists of a shaped rod and different sizes of metal weights (usually , , 1, 2, and 5 pounds) placed on a flat surface (rest).
The steps in measuring trigger pull with trigger weights are as follows:
- For single-action trigger pull, cock the firearm. For double-action trigger pull, do not cock the firearm.
- Place the trigger under the top portion of the rod.
- Slowly lift the firearm upward with the rod, bringing force on the trigger.
- If the weights come off the rest without the firearm discharging, add more weight to the rod.
- If the firearm discharges before the weights come off the rest, remove weight from the rod.
- Continue until the least weight required to cause the firearm to discharge without the weights leaving the rest is determined.
The steps in measuring trigger pull with a spring scale are the following:
- Cock the firearm.
- Attach one end of the scale to a fixed object and position the other end against the trigger.
- Slowly pull away from the fixed object until the firearm discharges.
- Record the pounds of pressure required to discharge the firearm as indicated on the scale.
Digital trigger pull scales operate in a similar way to spring scales. Calibrate and use digital scales as specified by manufacturers instructions.
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